Few days ago I made a interesting benchmark of 4 different PHP Versions !
I updated from 5.3.x to 5.4.x ... and made tests with the brand new 5.5.x Version - 32 and 64bit.
And I had an real AHA effect.

The Test are made on an i7 3770K with 16GB RAM; 560Ti, Samsung 840pro SSD and Abyss 2.9.0.1 64bit on an VM-Ware 10 Image with Server 2008R2 64bit.
The benchmark only says that the math function are optimized with every major version ...

In summer I'll change to PHP 5.5. 64bit - it runs very stable with activated Opcache.
Has anyone also made speed tests with different PHP versions? Or tipps to optimize and speed up PHP.

Better compilers explain the 5.3 to 5.4 figures. The activation of the opcode cache by default in 5.5 explained the AHA effect in the new series._________________Support Team
Aprelium - http://www.aprelium.com

Not sure if you're using the preconfigured PHP from Aprelium, or installing PHP from PHP, but if it is the latter, opcode caching is disabled by default in your PHP.INI -- enable that, and you'll see even more improvements.

As for using x64 on what appears to be Windows -- it's still not considered an ideal situation for a server environment (but then again, neither is Windows).

What is the main driver to use x64 for you?_________________Portfolio: Robert Lerner